What causes ice dams?
Ice dams form when melted snow refreezes at roof edges. Three things are required for an ice dam to form: snow, heat to melt the snow, and cold to refreeze the melted snow. The heat from inside the home rises through the ceilings and into the attic. If the attic is sufficiently ventilated, heat is dispersed, leaving the attic area and roof deck as cold as the outside air. Without sufficient attic ventilation, however, heat collects under the roof deck and melts the snow on the roof. Melted snow rolls down the roof slope to the eave and refreezes before dripping off the roof. As this process continues, the layer of ice at the eave gets thicker; eventually causing a "dam" that traps the melted snow behind it and creates a pool of water. This pool of water can creep under the shingles and into the home causing damage to walls, ceilings, insulation, and other areas.
What to do if you have an ice dam
Large icicles extending from eaves and gutters are often signs of an ice dam. Water coming in through ceilings or windows is another sign. If you have these conditions or to prevent these conditions, you should remove snow from at least the first three feet of the roof with a "roof rake". Roof rakes are available at most hardware stores. Never walk on a snow-covered roof. Make sure you work from a ladder. Never put rock salt or sodium chloride on the roof or the shingles will be damaged. Potassium chloride or calcium chloride can be used safely to melt ice. Removing an ice dam can be quite dangerous. Consider contacting a professional to remove snow and ice from your roof.
Long-term prevention of ice dams
Ice dams can be prevented by controlling the heat loss from the home. Proper ventilation and insulation of the attic are the best ways to prevent ice dams.Icicles forming on the edge of the roof are a sign of a ventilation problem. Homeowners should consult a qualified roofing or insulation specialist for recommendations tailored to their situation.
While it's extremely rare that an ice dam will damage the roof itself, we do see claims for sagging or collapsed ice-filled gutters, water damaged ceilings, peeling paint, damaged plaster, and wet insulation. As with all water claims, it's very important to dry the affected areas as soon as possible to avoid water related complications.
On a typical Home and Highway® HO3Z policy, damage to the structure is covered unless specifically excluded or limited in the policy. There's no exclusion that applies to damage caused as the result of an ice dam, so the costs associated with remediating the interior water and repairing the damage would be covered.
Personal property is covered only against the specified perils in the policy. Damage caused as the result of ice dams is not one of the specified perils, so damage to contents is not covered on an un-endorsed policy. If the insured has added the WB659 Special Personal Property Coverage Form or the Protector Plus package (which includes the WB659), they are afforded the same "all-risk" coverage found on Coverage A and there would be coverage for damaged personal property. Simply removing ice or snow from the roof when there is not any damage to the home is a maintenance issue and would not be covered.